Abstract [en]

The problem of tuyere refractory wear has been studied in an air-water model using a 4 mm diameter tuyere. Erosion tests, with boric acid (H(3)BO(3)) disks as refractory simulators, and measurements of back-attack frequency were carried out. The erosion pattern showed two distinct features; isolated elliptical pits and a continuous irregular shear wear pattern. The influence of the surface hardness and gas flow rate on these features was investigated. Pitting was found most frequently on disks formed at the lowest pressure (10 tons), but for pressures greater than 20 tons little difference was seen between disks. When the gas flow was in the bubbling regime, pitting was observed inside the region closest to the tuyere tip, with a maximum at the transition to jetting flow. Occasionally, pits could still be observed when the gas flow rate was rather high (NMa=1.82). The irregular wear pattern appeared independent of disk surface properties, however, sensitive to the gas flow rate. In the bubble flow regime, the wear was seen only outside a certain radius, which corresponds well to the radius of the bubbles. In the jetting regime, the wear was also observed close to the tuyere. The disk weight loss showed a maximum in the bubbling-to-jetting transition region, where the back-attack frequency also reached a maximum. The results support the idea that cavitation erosion, through liquid microjet pitting, is the main mechanical wear agent. A model for the generation and